1. Field of the Invention
Aspects of the present invention relate to a carbon nanotube hybrid system using carbide-derived carbon, an electron emitter including the same, and an electron emission device including the electron emitter, and more particularly, to a carbon nanotube hybrid system that can be prepared using a less expensive method than that used to manufacture conventional carbon nanotubes and that has excellent uniformity and a long lifetime, an electron emitter including the same, and an electron emission device including the electron emitter.
2. Description of the Related Art
In general, electron emission devices can be classified into electron emission devices using hot cathodes as an electron emission source and electron emission devices using cold cathodes as an electron emission source. Examples of electron emission devices using cold cathodes as an electron emission source include field emitter array (FEA) type electron emission devices, surface conduction emitter (SCE) type electron emission devices, metal insulator metal (MIM) type electron emission devices, metal insulator semiconductor (MIS) type electron emission devices, and ballistic electron surface emitting (BSE) type electron emission devices.
FEA type electron emission devices operate based on a principle that a low work function material or high beta function material as an electron emission source easily emits electrons due to an electric charge difference under a vacuum condition. Recently, tip-shaped structures mainly formed of Mo, Si, or the like; carbonaceous material, such as graphite, diamond like carbon (DLC), or the like; and nano materials such as nanotubes, nanowires, or the like have been developed as electron emission sources for FEA type electron emission devices.
In an SCE type electron emission device, a first electrode faces a second electrode on a first substrate, and a conductive thin film having fine cracks is located between the first and second electrodes. These fine cracks are used as an electron emission source. In this structure, when a voltage is applied to the device, current flows in the surface of the conductive thin film and electrons are emitted through the fine cracks acting as an electron emission source.
MIM type electron emission devices and MIS type electron emission devices respectively include an electron emission source having a metal-dielectric layer-metal (MIM) structure and an electron emission source having a metal-dielectric layer-semiconductor structure. When a voltage is applied between the metals or between a metal and a semiconductor separated by a dielectric layer, electrons move, are accelerated, and are emitted from the metal or semiconductor having a higher electron charge to the metal having lower electron charge.
BSE type electron emission devices operate based on a principle that when a semiconductor is miniaturized to a dimension smaller than a mean free path of the electrons of the semiconductor, electrons travel without being dispersed. In particular, an electron supply layer formed of a metal or a semiconductor is formed on an ohmic electrode, an insulating layer and a thin metal film are formed on the electron supply layer, and a voltage is applied to the ohmic electrode and the thin metal film to emit electrons.
In addition, FEA type electron emission devices can be categorized into top gate type electron emission devices and bottom gate type electron emission devices according to locations of cathodes and gate electrodes. Furthermore, FEA type electron emission devices can be categorized into diode emission devices, triode electron emission devices, tetrode electron emission devices, etc., according to the number of electrodes used.
In the electron emission devices described above, carbon-based materials, included in an emitter, for example, carbon nanotubes, which have good conductivity, electric field concentration, electric emission properties and a low work function, are commonly used.
However, carbon nanotubes commonly have a fiber shape having a high field enhancement factor β, and fiber type carbon nanotube materials have many problems, such as poor uniformity and a short lifetime. Further, when fiber type carbon nanotubes are manufactured in a paste, an ink, a slurry, or the like, problems occur during manufacturing processes compared with other particle type materials, and raw materials of the fiber type carbon nanotubes are expensive.
Recently, research on materials consisting of inexpensive carbide-based compounds that can be substituted for carbon nanotubes have been conducted in order to overcome these disadvantages (Korean Patent Publication No. 2001-13225).